update delete select and load gridview using linq in asp.net using c#

  protected void btnModify_Click(object sender, EventArgs e)
    {

        DataClassesDataContext dbcontext = new DataClassesDataContext();
        var VideoList = (from vl in dbcontext.VideoTables where vl.VideoID == Convert.ToInt32(ViewState["VideoID"]) select vl).Single();
        if (VideoList != null)
        {
            VideoTable vt = new VideoTable();
            VideoList.VideoHeading = txtVideoHeading.Text;
            VideoList.VideoLink = txtVideoLink.Text;
            VideoList.Remark = txtRemark.Text;
        }
        try
        {
            dbcontext.SubmitChanges();
            loadVideoGrid();
            BAL.Sangram.alert("Record Updateed Successfully.....", "", true);
            return;
        }
        catch
        {
            BAL.Sangram.alert("Some Error Occured.....", "", true);
            return;
        }
    }
----------------------------------------------------------
 protected void gdvVideo_RowDeleting(object sender, GridViewDeleteEventArgs e)
    {
        string videoId = gdvVideo.DataKeys[e.RowIndex]["VideoID"].ToString();
        DataClassesDataContext dbcontext = new DataClassesDataContext();
        var vID = (from VlR in dbcontext.VideoTables where VlR.VideoID == Convert.ToInt32(videoId) select VlR).Single();
        try
        {
            dbcontext.VideoTables.DeleteOnSubmit(vID);
            dbcontext.SubmitChanges();
            loadVideoGrid();
            BAL.Sangram.alert("Record Deleted Successfully.....", "", true);
            return;
        }
        catch
        {
            BAL.Sangram.alert("Some Error Occured.....", "", true);
            return;
        }
    }
-----------------------------------------------------------------
protected void gdvVideo_SelectedIndexChanging(object sender, GridViewSelectEventArgs e)
    {
        ViewState["VideoID"] = gdvVideo.DataKeys[e.NewSelectedIndex]["VideoID"].ToString();
        DataClassesDataContext dbcontext = new DataClassesDataContext();
        var vidiolist = from vl in dbcontext.VideoTables where vl.VideoID == Convert.ToInt32(ViewState["VideoID"]) select vl;
        if (vidiolist != null)
        {
            txtVideoHeading.Text = vidiolist.FirstOrDefault().VideoHeading.ToString();
            txtVideoLink.Text = vidiolist.FirstOrDefault().VideoLink.ToString();
            txtRemark.Text = vidiolist.FirstOrDefault().Remark.ToString();
            btnModify.Visible = true;
            btnSave.Visible = false;
        }
    }
---------------------------------------------------------------
    private void loadVideoGrid()
    {
        DataClassesDataContext dbcontext = new DataClassesDataContext();
        var vedioList = from vl in dbcontext.VideoTables select vl;
        gdvVideo.DataSource = vedioList;
        gdvVideo.DataBind();
    }